FIG. 14 is an external view of the existing sway rod type limit switch 200, illustrating a state of the sway rod 201 of the sway rod type limit switch 200 at the free position under no external force. FIG. 15 is a top perspective view of the existing sway rod type limit switch 200 with its top cover 210 removed, illustrating a state of the sway rod 201 of the sway rod type limit switch 200 at the extreme position. As shown in FIG. 15, a rotating shaft 203 is contained inside the housing 202 of the existing sway rod type limit switch 200. Moreover, a resin cam 204 is mounted at one end of the rotating shaft 203. A transmission protruding part 205 and a limit protruding part 206 protruding towards the outside of the radial direction of the cam 204 and extending along the circumferential direction of the cam 204 are formed on a part of the external circumference of the cam 204. Besides, the other end of the rotating shaft 203 extends out of the housing 202 and is fixedly connected with the base end of the sway rod 201 outside the housing through a threaded component 207. A stress roller 208 is arranged at the free end of the sway rod 201. Therefore, when the external force generated by the impact of the controlled equipment and the like is applied on the stress roller 208 to enable the sway rod 201 to sway, the sway rod 201 drives the rotating shaft 203 to rotate, so as to enable the cam 204 mounted on the rotating shaft 203 to rotate at the same time. Then, the transmission protruding part 205 drives the switch component (not shown in the figure) located below the cam 204 to act, thereby controlling the on/off of the controlled equipment. In addition, a torsion spring 220 is wound on the external circumference of the rotating shaft 203. The rotating shaft 203 can restore to the initial free position as shown in FIG. 14 under the action of the torsion spring 220 when the external force applied on the stress roller 208 disappears, so that the switch component restores to its initial on-off state.
The limit protruding part 206 is used for limiting the swaying of the sway rod 201 and the rotation of the rotating shaft 203. Two bosses 209 protruding inside the housing 202 are respectively formed on the internal surfaces at left and right sides of the housing 202. When the sway rod 201 sways to the extreme position as shown in FIG. 15, the limit protruding part 206 is abutted with the boss 209, so that the sway rod 201 and the rotating shaft 203 stop rotating. FIG. 15 illustrates the state of the sway rod 201 which sways clockwise from the free position shown in FIG. 14 to the extreme position at which the limit protruding part 206 is abutted with the boss 209 of one side and therefore limited. Likewise the state of the sway rod 201 which sways counterclockwise from the free position shown in FIG. 14 to the extreme position at which the limit protruding part 206 is abutted with the boss 209 of the other side and therefore limited.
One example of background art is disclosed in CN 100449664C. The counterpart U.S. case to CN 100449664C is U.S. Pat. No. 6,627,827.